Ar″cha‐ism (�), n. [Gr. αρχαἰ̈σμόσ, fr. αρχαἰ̑οσ ancient, fr. αρχἤ beginning: cf. F. archaïsme. See Arch, a.] 1. An ancient, antiquated, or old-fashioned, word, expression, or idiom; a word or form of speech no longer in common use.
2. Antiquity of style or use; obsoleteness.
A select vocabulary corresponding (in point of archaism and remoteness from ordinary use) to our Scriptural vocabulary.
De Quincey.